HIIT study: Servers run well around zero degrees

Lots of energy can be saved by using outside air directly for cooling in data centers in the north. In a study by researchers of Helsinki Institute for Information Technology HIIT and the University of Helsinki, computers functioned correctly over extended periods of time when run in harsh winter temperatures. Commercial, off-the-shelf computers ran well even when the outside temperature was -22C (-8F).

In the north, cooling data centers consumes lots of energy. According to an analysis published by HP in February 2009, data centers would be the sixth-largest consumer of electricity if they were classified as a separate industry. Research conducted in Helsinki Institute for Information Technology HIIT and the University of Helsinki aims at finding energy-saving potential in computing.

In the still on-going experiment by Professor Jussi Kangasharju and Researcher Mikko Pervilä servers have been kept running in a tent on a roof terrace in Finland for half a year. This is the first time computers have been run in a scientific experiment covering so wide a range of temperatures and humidity. Researchers follow how the servers run when temperatures and humidity changes naturally and the computers are only protected from direct snow, water and sunshine. When the outdoor temperatures have gone down to -22C (-8F), the temperature in the tent has been around -5C (+23F) because the computers heated up the tent.

- We are surprised at how well the servers have run compared to computers indoors. This means that data centers can be cooled in Northern Europe and Northern America with outside air efficiently without energy-consuming cooling and without computers functioning in a less stable manner due to changes in temperature and humidity, says Professor Kangasharju.

The study has been published in the Proceedings of the first ACM SIGCOMM workshop on Green networking.

Helsinki Institute for Information Technology HIIT is a joint research institute of Aalto University and the University of Helsinki for basic and applied research on information technology.

More information:

Jussi Kangasharju, professor

Helsinki Institute for Information Technology HIIT

Tel. +358 50 415 1708

e-mail: firstname.lastname@hiit.fi

Published article:


Pictures about the experiments in Flickr:


Presentation on the experiment held in Green Networking 2010:


Created date

11.10.2010 - 12:21

Professor Esko Ukkonen invited to the Estonian Academy of Sciences

Professor Esko Ukkonen has been invited to the Estonian Academy of Sciences as a foreign member.

Esko Ukkonen has had contacts to the computer science community in Estonia from the beginning of the 1990s, and he has supervised the work of several Estonian postgraduates. The Estonian Academy of Sciences has 78 ordinary and 21 foreign members.

The First Europe-China Workshop on Big Data Management

Some attenders of this workshopThe first Europe-China workshop on big data management was successfully held on the 16th of May, 2016 at the Department of Computer Science, University of Helsinki. 

This one-day workshop organized by Prof. Jiaheng Lu (University of Helsinki), Prof. Xiaoyong Du (Renmin University of China), and Prof. Christian S. Jensen (Aalborg University, Denmark). The aims of this workshop were to gather experts in big data management to exchange views on cutting-edge data management problems and create opportunities for establishing new collaborations between EU and China computer scientists.

Inter-university research and training centre on information security

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The idea is to build bridges to the industries and gain their support for the education, and e.g. grants for MSc students coming from outside the EU, the head of the Department of Computer Science, Sasu Tarkoma, says.

Computer science undergraduate Petteri Timonen awarded in US science competition

Petteri Timonen, 19, came second in his category of the Intel International Science and Engineering Fair (ISEF) in Phoenix, Arizona.


On Friday, 15 May, Timonen, who is studying computer science at the University of Helsinki, was awarded a grant worth 1500 USD, some 1330 euros, in the Systems Software category of the Intel ISEF science competition.
As his entry, Timonen submitted a software tool he developed for Finland’s Red Cross to make mobile blood runs around the country as cost-effective as possible. Timonen implemented his tool in cooperation with the Blood Service.

The tool has gained international attention, as no tool like it seems to have been developed anywhere else. Timonen has also negotiated with the American Red Cross by email.